Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/29/20


Area Forecast Discussion
National Weather Service Caribou ME
1024 PM EDT Sun Jun 28 2020 .SYNOPSIS... An upper low will over New England will prevail into mid week. Unsettled weather will accompany it especially over western and Downeast areas as surface low pressure develops off the southern New England coast overnight and remains south through mid week. High pressure approaches the region Thursday, followed by a cold front from the north Thursday night and Canadian high pressure for Friday. && .NEAR TERM /THROUGH MONDAY/... 10 PM Update... Steady rainfall ongoing across the w and nw areas this evening w/intensity dropping off in the last few hrs. The radar showed some enhanced echoes pushing nwrd w/GLM satl lightning product showing increased potential for some lightning. Decided to keep isold tstms in for central and northern areas overnight. Heavy rainfall with the threat for overnight. Higher resolution guidance having a hard time catching the individual heavier cells. The latest RAP and HRRR were closest on grabbing the general area of activity. Adjusted the QPF through 12z to catch the higher totals across the w and nw areas. Temps have fallen back into the 60s. Along the coast, temps were in the upper 50s w/some stratus. Temps will drop a few more degrees and then level off as clouds fill back in overnight. Decided to areas of fog in for the coast and expanded this up into the nw areas that received the heavier rainfall earlier. Patchy fog elsewhere. Areas that see some partial clearing which appears to be showing up on the latest ir satl imagery across eastern areas could see a more widespread fog. Midnight crew can monitor this further. Previous Discussion... Upper low continues to dominate the weather across the forecast area through Monday. This will result in scattered showers and isolated thunderstorms, mainly early this evening. Patchy fog is once again expected tonight Downeast, especially along the coast. As surface low develops to our South overnight, expect the chance for rain to increase across Downeast areas by daybreak Monday. The forecast soundings are showing deep moist profiles across the western and Downeast portions of the forecast area on Monday, with pwat values around 1.5". The potential is there for locally heavy rainfall, especially from the central Maine highlands through Downeast. The coldest air aloft associated with the upper low on Monday remains to our south and west. With more in the way of cloud cover on Monday and easterly flow, potential for thunder looks lesser, and with little in the way of significant SB CAPE expected, only a mention of isolated thunder seems warranted. Across the far north, expect lesser chances for rainfall on Monday, as deeper moisture and forcing remains across the central highlands and Downeast areas. High temperatures on Monday are expected to be cooler as well, with more in the way of cloud cover expected, along with northeast winds. This will confine high temperatures mainly to the upper 60s to lower 70s across the region. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Upper low pres will remained anchored ovr Cntrl New Eng thru this tm, with this feature beginning to weaken by Wed. The sfc low near Cape Cod will be strongest Mon ngt, with this system slowly weakening ahead of the upper low beginning Tue as whats left of low to mid layer baroclinicity gets used up. This pattern will bring the best chc of shwrs and aftn/eve tstms to Wrn and Downeast areas each day, with a definite diurnal sfc htg component adding to the 18-00z 6hrly QPFs and somewhat to the latter pts of the 12-18z and early ptns of the 00-06z QPF tm frames. Hi temps will be held down most on Tue with the great cld cvrg canopy arnd the upper low. Aftwrds, cld cvr will begin to diminish ovr Nrn and ern ptns of the FA late Tue ngt into Wed as the upper low nudges slightly further SSW. This will likely result in an inverted Hi temp pattern ovr the FA with the N warmest due to greater sunshine. Outside of Mon ngt, where NE grad flow will be a little stronger to offset development, we mention late ngt/erly morn patchy fog. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Shwrs and thicker cld cvr will exit to the S as whats left of the upper low opens up and moves SE of Cape Cod. This will allow much warmer 925-850 mb temps from Cntrl Can to enter the FA from the NW for all of the FA. Any late ngt patchy fog will rapidly dissipate within a couple of hrs after sunset, with very warm aftn hi temps xpctd. A fairly strong cold front from the N will enter Nrn areas of the FA by erly Thu eve, crossing S of the Downeast coast by late Thu ngt as a s/wv alf moves S from Nrn QB into the Ern Maritimes. We indicate a chc of shwrs/tstms just ahead of this feature beginning across the far N late Thu aftn and contg ovr Cntrl and Downeast areas into the ovrngt. Fri and and Sat look to be cooler and much more drier and comfortable behind the front as sfc high pres from Hudson bay prevails. Hi temps Fri and lows Fri ngt will be coolest with recovering hi temps by Sat aftn. Sun will cont dry and a little warmer yet with most lower trrn lctns N of the immediate coast reaching back into the 80s as sfc winds become WSW with the sfc hi crossing SE of the Gulf of ME. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... NEAR TERM: VFR at the Aroostook county terminals through early this evening will give way to developing MVFR ceilings after midnight. MVFR ceilings and scattered showers are expected on Monday. Light south to southeast winds tonight around 5 kt. VFR at KBGR/KBHB early this evening will give way to IFR in developing low ceilings and patchy fog this evening. IFR conditions will persist at those terminals through Monday morning with improvement to MVFR Monday afternoon, with showers expected. NE winds 5 to 10 kt expected on Monday. SHORT TO LONG TERM: Mon Ngt - Wed Ngt...all TAF sites VFR late morn into eve and MVFR/IFR late ngt into erly morn with ST clgs in patchy fog. Clgs/vsbys briefly MVFR late morn into erly eve with tstms/heavier shwrs. Lgt winds. && .MARINE... NEAR TERM: Wind/seas will remain below SCA levels through Monday. Patchy fog and showers will reduce visibility to 1 to 3 NM at times through Monday. SHORT TO LONG TERM: No dtmnstc pds of SCA seas xpctd attm, although wv hts may come close attms ovr outer MZ waters. Went with about 90 to 95 percent of blended wv guidance for fcst wv hts thru these ptns of the fcst. Initially wvs will be comprised of two spectral wv components Mon ngt and Tue, a short fetch 6 sec nwrd propagating group and a longer 10 to 12 sec background NE propagating swell component with the swell component prevailing from Tue ngt thru Thu. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Des Moines IA
631 PM CDT Sun Jun 28 2020 .DISCUSSION.../Tonight through Sunday/ Issued at 216 PM CDT Sun Jun 28 2020 .Overview... Our focus will remain set on storm development this evening and overnight, where severe storms are likely across northern Iowa. Periodic storms chances continue through much of the upcoming week with hot and humid conditions each day. .Details... Morning convection gradually diminished across the state this morning as it lifted north into central Iowa. The weak warm front by early afternoon drapes across central into northern Iowa roughly from Fort Doges to Marshalltown and down towards Ottumwa. There have generally been two main areas for convection today, the first across southern Iowa within the warm sector and the second in west-central to north-central Iowa along the nose of the frontal convergence. The latter has formed within the remnants of the morning MCV where surface vorticity is maximized, resulting in a funnel report. Convection will continue to bubble across northern Iowa this afternoon, with some strengthening expected around 00z a this complex is met by advancing surface low pressure out of South Dakota. Of the HREF suite, the HRRR is the furthest north with solutions varying from southern Minnesota to southern Iowa. While CAMs have struggled with convection lately, thus far the HRRR has had the best handle on the overnight/morning convection. That said, keying in on one solution over another is risky in this environment and wouldn`t be surprised if a more southerly solution unfolds, due in part to a PV anomaly over western Kansas which could anchor convection a little south. Regardless of where convective initiation occurs, severe storms will be well supported. Model sounding indicate CAPE of 3500-4000+ J/kg with steep mid level lapse rates. Shear is generally in the 30 kt range to support initial discrete convection before upscale growth. Hodographs exhibit excellent low-level curvature with 0-1 km SRH of 150-200+ across northern Iowa. Initial discrete storms will certainly have tornadic potential with threat transitioning to wind and hail as storms grow upscale. Lastly, in addition to the sever threat, heavy rain could result in flood concern across northern Iowa with pwats of nearly 2 inches. The rest of the period remains somewhat uncertain with periodic chances for convection through much of the upcoming week. While everyday will not be a washout, narrowing for windows for convection continues to be a difficult task with subtle shortwaves poorly handled by synoptic models. One area that has become more clear is Wednesday as the western cut-off low moves east. Model show some agreement in the progression of this system and it appears that more severe weather could be possible, though details are lacking. By the end of the week the pattern begins to break down with drier conditions possible into the holiday weekend. Aside from the uncertainty in convective development, hot and humid conditions will remain in place all week as warm gulf moisture streams into the midwest. Daytime highs in the upper 80s to low 90s with dewpoints in the low 70s will make it feel more like the upper 90s to near 100. With this first extended hot, and moreso humid, period of the year, heat safety will certainly be a concern. && .AVIATION.../For the 00Z TAFS through 00Z Monday evening/ Issued at 631 PM CDT Sun Jun 28 2020 Only concern for aviation weather in the TAF period is prospect of TSRA and associated reduced vsby, low cigs, gusty winds overnight. Unfortunately confidence in probability and location of any storms is lower than usual, so have included VCTS groups over most likely hours at all terminals except OTM, and will update/amend as needed based on radar trends overnight. Any storms that do form will be clear of the area by 12Z Monday, with only VFR conditions expected thereafter. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...Hagenhoff AVIATION...Lee
Area Forecast Discussion
National Weather Service Grand Forks ND
1003 PM CDT Sun Jun 28 2020 .UPDATE... Issued at 957 PM CDT Sun Jun 28 2020 Line of storms has develop from Bismarck to SD border which is farther south of previous thinking. This activity will spread eastward across southern ND moving into SE ND weakening as it does. UPDATE Issued at 638 PM CDT Sun Jun 28 2020 North south boundary has been the focal point for thunderstorms across central ND this afternoon and evening. Across the eastern portions of the state breezy and warm conditions persist with temps in the mid to upper 80s and dew points in the mid to upper 60s. CAMs continue to indicate the activity in the west will stay west until short wave energy evident in western SD convection pushes east merging with or aiding in development of more storms on the southern end of the convergence line in western ND. This activity will then move into western portions of the CWA somewhere in the 12AM to 3AM time frame. Shear is expected remain weak with HRRR and NAM indicating 0-3km values less than 25kts. Combined with increasing CIN during the early morning hours convective activity should be on a downward trend in strength as it moves into the area. That said still too early to rule out any wind potential with respect to the severe threat. && .SHORT TERM...(This evening through Monday night) Issued at 240 PM CDT Sun Jun 28 2020 Hot and gusty conditions will dominate the forecast through the rest of the afternoon. Southeast winds are already gusting over 35 mph and will continue until around sunset. Temps will max out in the upper 80s to lower 90s, with heat indices in the mid 90s, warmest near central ND. CAMs are still trying to resolve the evolution of convection expected to initiate in western and central ND along an north- south oriented stationary/quasi warm front. The front sits just west of the Turtle Mtns south to near Dickinson. Supercells and multicell clusters are expected to develop along this front mid to late afternoon, although storm trajectories should be northerly amidst deep layer southerly flow. However there may be the tendency for new updrafts to propagate east or southeast which may bring these strong to severe storms closer to the Devils Lake basin (namely Benson and Towner counties) around or after sunset. Should this happen, the threat for very large hail, gusty winds, heavy rainfall, and a slim chance for a tornado. 12Z HREF continues its trend of UH tracks into the Devils Lake basin and now the James River Valley, especially after 1 AM as a shortwave moves through western ND. Despite moderate to strong instability feeding storms (including high DCAPE), deep layer shear is expected to be lacking, especially east of central ND. Early morning storms are likely to be linear, and with the a window of DCAPE feeding into convection, high wind gusts with thunderstorms will be possible. Given the trends of latest hires guidance, keeping a slight chance for storms mentioned in the forecast in these areas, some of which may be severe. Monday will be similar to today, except may a little less wind and more heat. Temperatures and dew points should be a touch higher tomorrow as thermal ridge edges closer over the area and moisture advection continues. Highs in the upper 80s to mid 90s Monday combine with dew points in the 70s to bring heat indices well into the 90s for the Red River Valley and west. Some locations in southeast ND could see heat indices exceed 100 degrees for a brief period in the afternoon, which may require heat headlines. Storm chances again exist for portions of eastern ND late Monday, some of which may be strong to severe bringing hail and gusty winds. .LONG TERM...(Tuesday through Sunday) Issued at 240 PM CDT Sun Jun 28 2020 Tuesday and Wednesday...Upper low/trough over the western CONUS becomes more negatively tilted by Tuesday. There will continue to be warm, moist air moving into the Northern Plains ahead of the surface trough, although think that convection will remain capped for at least part of the day. Several weak lead shortwaves moving through should push the surface trough axis into eastern ND by evening, and will be the focus for strong to severe thunderstorm development. Instability will continue to be very strong with over 3000 J/kg of ML CAPE possible. On the other hand, with the main upper system still well to the west the deep layer bulk shear is very weak. Some pulsey severe storms and heavy rain from slow movement seem most likely at this point. The upper ridge will move further east by Wednesday, with improved upper level flow and stronger deep layer shear. Hard to tell the exactly how the instability on Wednesday will play out given earlier convection, but PWAT values remain in the higher percentiles according to the NAEFS and chances continue to remain high for precipitation. Thursday through Sunday...The main upper trough lifts northward into Canada on Thursday, leaving southwesterly flow aloft turning into a ridge for the end of the week. Weak high pressure will keep things dry and warm for Thursday before conditions heat up more for Friday as south winds return. Independence Day looks quite toasty with high heights, then ridge riders possibly bringing some convection, although placement and timing is impossible to tell at this point. Heat and thunderstorm chances continue into Sunday although moderating a bit as the ridge starts to break down. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 638 PM CDT Sun Jun 28 2020 Wind continue to gust from 20 to 35kts at all TAF sites. Will see gusts wane this evening. Will keep the mention of thunder out of all tafs for now. There remains the possibility between 6 and 12Z at DVL, GFK and FAR. Though confidence is low in occurrence. Will keep the mention of MVFR CIGs for the early morning hours. Tomorrow should see less wind. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...JK SHORT TERM...CJ LONG TERM...JR AVIATION...JK
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
650 PM CDT Sun Jun 28 2020 .SHORT TERM...(This Evening through Monday Night) Issued at 325 PM CDT Sun Jun 28 2020 Short term forecast remains largely focused on the remnant MCV that is moving its way north-northeastward across the area. GOES-16 water vapor imagery shows the spatial coverage that this feature has, causing cloud coverage from eastern SD, through southern MN and down into western IL. The trailing southwestern edge of the cloud cover will continue on the decline, allowing daytime heating to resume throughout the rest of the afternoon. With dewpoints as of 3 PM in the mid 60s to lower 70s and temperatures increasing with cloud coverage dissipating, it is no surprise that ample CAPE (~3000-4000 J/KG) will be parked over the area this afternoon. Effective bulk shear values are highest over NW IA, where 40+ knots are available, but the shear drops off as we head into the evening making organized storms more difficult to maintain. Given the large amounts of instability and good shear early on, if any storms are do form in this environment they will be able to produce hail to the size of golf balls. A tornado in NW IA can not be ruled out early on either, as low LCLs coincide with areas of enhanced 0-1 km storm relative helicity. As storms begin to lose their composure, DCAPE values greater than 1000 J/KG will shift the risk towards more of a wind threat as storms track eastwards along the anticipated cold pool. Vast majority of HREF members had storms initiating in NE Nebraska, but the HRRR runs since this morning have been putting initiation in NW Iowa. Most high resolution guidance didn`t handle the movement of the MCV very well this morning, so tend to trust the evolution of the HRRR which favors NW Iowa. If there are any lingering storms Monday morning in NW IA and SW MN courtesy of the low level jet, they will continue to trail off to the east leading to a hot and humid day. Under southwesterly flow aloft, south-southeasterly flow near the surface will remain in place throughout the day, with gusts up to 25 mph under a strong inversion aloft which should prevent any afternoon storms from firing. With weak low-mid level cloud coverage, temperatures will climb into the low to mid 90s with dewpoint temperatures rising into the low to mid 70s. Heat index values are looking warmest primarily west of the I-29 corridor, where heat indices greater than 100 are possible with some pockets approaching 105. Have collaborated a heat advisory with neighbors for areas where this is most likely, but may need to be expanded. The winds will calm down a bit into the overnight period, with low temperatures staying rather warm in the low to mid 70s. .LONG TERM...(Tuesday through Sunday) Issued at 325 PM CDT Sun Jun 28 2020 The trough over the western CONUS remains in place, leaving us under south-southwesterly flow aloft along with a strong inversion in place. Temperatures will be a little cooler, with highs in the upper 80s to lower 90s and heat indices currently expected to remain largely in the 90s. As the trough axis wobbles its way closer to our area, the surface low will get close to our area creating a strong pressure gradient which will cause our winds to remain breezy with gusts in the 25-30 mph range. The surface low is currently expected to break off into two lows, one heading to our south and the other staying well off to our north. The cold front being dragged eastwards by the southerly low will likely set off scattered showers and thunderstorms in central SD during the afternoon, and will attempt to fire off more storms in eastern SD overnight. While CAPE values exists out ahead of the front ~3000 J/KG, the best combination of good shear (40-45 knots) and CAPE (~2000 J/KG) exists in an elevated narrow corridor behind the front. Some frontogenesis and positive vorticity advection will be aiding these storms aloft, and working together with steep mid- level lapse rates will likely result in a couple strong to severe thunderstorms. This threat is highlighted nicely in SPC`s day 3 severe weather outlook. Scattered shortwaves continue to move overhead throughout the day on Wednesday, keeping chances for showers and thunderstorms into the early evening. Drier air and upper level ridging moves in early Thursday morning, which should keep rain chances low into the weekend. A stray showers cannot be ruled out for 4th of July fireworks at this point although it is looking unlikely, with otherwise warm and moderately breezy conditions expected for the holiday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 641 PM CDT Sun Jun 28 2020 South and southeast winds will remain gusty through sunset. These winds continue overnight, but gusts will decrease in frequency and strength. Scattered thunderstorms are possible in northwest Iowa this evening into the early overnight, including for locations such as KSPW (Spencer IA). Shortly after sunrise, gusty south winds again become gusty with mostly cloudy skies. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Heat Advisory from 1 PM to 8 PM CDT Monday for SDZ038-039- 052>054-057>061-063>066-068-069. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...APT LONG TERM...APT AVIATION...VandenBoogart
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
735 PM CDT Sun Jun 28 2020 ...Aviation Update... .SHORT TERM...(This evening through Monday) Issued at 259 PM CDT Sun Jun 28 2020 Biggest problem in the short term will be determining if a stray thunderstorm develops over the CWA or moves in from the west this evening. Going with a dry forecast this afternoon/tonight but chances are not exactly zero as an isolated shower/thunderstorm could pop up. Coverage would be extremely scant, though. Although the 12Z run of the HRRR shows a couple of pop-up thunderstorms in our southern CWA and the NAMnest tries to give us a little convection in our east, I suspect that we will be too capped to allow much activity to develop, despite the high CAPE environment. Our best shot at an isolated thunderstorm would be in our far east/northeast to near GI/Hastings, it appears. Developing cumulus today should have little chance of much vertical development, however. Hazy skies are largely a result of some Saharan sand. Some hi-res/short term models bring dying convection close to our western CWA this evening, but the 850 mb theta-e ridge will likely be skewed just east of our CWA, and will offer little help to struggling convection in western/central Nebraska. With higher dewpoints will come low temperatures remaining in the 70s for most tonight. For Monday/Monday evening, 700 mb temps will be in the 15-16C range, and should pretty much quell any chance of thunderstorm development under strong subsidence. Dewpoints will be every bit as high as Sunday, with heat index pushing to near 100 or so, especially in our east, as our actual high temperatures reach well into the 90s. Models are giving me a bit of a cool-down for 850 mb, and even models that have done well on our recent hot days, are giving me temps cooler than our previous forecast. I`m not comfortable knocking down temps all that much as it looks like we could have some feedback issues going on. .LONG TERM...(Monday night through Sunday) Issued at 259 PM CDT Sun Jun 28 2020 Biggest problem will be determining storm chances and potential severity for Tuesday/Tuesday night with potential shortwave trough and approaching cold front and trough/dry line. For Tuesday/Tuesday night, a spoke of energy rotating around the broadening northwest United States trough will give us a shot at some thunderstorms, possibly severe. The focus of synoptic support remains northwest/north of our CWA for the most part but we could have foci for convective development despite the limited help synoptically. A strong baroclinic zone will exist Tuesday along and ahead of a cold front, with a possible pre-frontal trough/dryline to potentially complicate things. MLCAPE of 3000+ J/kg There could be a triple point scenario somewhere near our area as well, possibly in our western/northern CWA, although deep layer shear does not look incredibly impressive. A hindrance to convection will be 700 mb temps of 15+C during the afternoon, but should give way to cooler temps by evening with diurnal cooling and height falls, and could allow elevated convection to occur. Nocturnal convection may be aided by low-level convergence of a low-level jet in the vicinity. Ensembles support a solution showing strengthening upper level ridging for the latter half of the week, ensuring warmer than normal temps into the 90s and low chances of thunderstorms/precip. Thursday would stand the very best chance of being dry of a forecast already on the dry side as a solid surface high builds in behind a cold front. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 734 PM CDT Sun Jun 28 2020 General overview: Confidence is high in VFR ceiling/visibility through the majority of the period, and in rain/thunderstorm-free conditions throughout. That being said, there are a few pesky question marks to consider (covered in more detail below). But before getting to those, will cover surface winds and visibility trends. Surface winds: Fairly straightforward. Direction will be remarkably consistent (from the south-southeast), with sustained speeds commonly 10-15KT and highest gust potential mainly 20-25KT and overall-strongest Monday afternoon. Visibility: Thanks to haze from Saharan dust, especially KGRI has been experiencing low-end VFR visbility for several hours now, and this will probably persist into much of at least the first half of the period. Not anticipating MVFR, but will run with 6SM HZ to cover this. Now onto the main uncertainties/possible pitfalls: 1) Some ceiling uncertainty: Some models/guidance are strongly hinting at MVFR stratus ceiling developing early Monday morning and perhaps lingering well into the day, while others are much-less aggressive. It`s a really tough call at this point to say whether this MVFR will actually develop, and if so, for how long. Am certainly not ready to run with prevailing MVFR yet, but feel it`s prudent to at least hint at this possibility. As a result, have introduced scattered MVFR clouds starting at 09Z. Should these lower ceilings develop in the morning, they would most likely scatter out and/or lift to VFR levels during the afternoon, but could remain low-VFR. 2) Possibility of very marginal low level wind shear (LLWS) overnight: Previous TAFs carried a formal LLWS mention, but latest guidance has backed off the overall-shear magnitude within the lowest few thousand feet above the surface, maxing it out closer to 25KT than 30+KT. As a result, opted to remove the official mention of LLWS with this issuance, but this will need monitored closely for possible "last minute" re-inclusion. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
533 PM MDT Sun Jun 28 2020 .SHORT TERM...(This evening through Monday) Issued at 137 PM MDT Sun Jun 28 2020 19Z UTC Water Vapor Imagery and RAP analysis continued to indicate broad westerly flow aloft over the CWA with short wave trough moving east across central Kansas, with much of CWA under the effects of subsidence behind it. At the surface flow aloft has become southeasterly with convergent area/trough once again setting up in western CWA. Have seem several attempts at convective initation, but as of now storms have not been able to develop. Main forecast concerns will be precipitation chances tonight and the heat and fire wx. While recent attempt at thunderstorms have failed, expect persistent forced ascent in eastern Colorado to get the ball rolling on a few thunderstorms by 23Z. As has been the case, strong cold pools likely. Instability weaker in formation area and CINH (especially ML) is much stronger to the east. Instability profiles, coupled with weaker low level shear profiles makes it seem doubtful that another MCS will march across the area. Expect a few storms to make it near the KS/CO border, with CINH increasing and cold pools likely surging ahead of the cells limiting the chances for precip to continue eastward are slim. Intense heating and convergence along dryline could possible spark a storm or two tomorrow afternoon. But with any frontogenetic forcing likely occurring on the dry side and strong CINH in the moist sector, seems doubtful anything will develop. Strong consensus that temps will hit the century mark in several locations, especially to west of dryline where dewpoints fall into the 30s. Winds will increase after 20z in this area, resulting in a window of critical fire weather conditions. .LONG TERM...(Tuesday through Sunday) Issued at 156 PM MDT Sun Jun 28 2020 Not much has changed since the last discussion. An upper-level deep trough moves out of the Great Basin and over the High Plains during the middle of the week. Tuesday, a surface front, associated with this trough, will move through the Tri-State region; producing a chance of showers and thunderstorms. After this front moves through the area an upper-level ridge builds into the area from Mexico and influences the area with dry conditions through Thursday. Temps will remain in the above normal range of the middle 80s to the middle 90s for the rest of the period; however, they will be slightly cooler than around 100 we will see on Monday. In addition, the dry conditions will produce elevated to near critical fire weather conditions, mainly for the west portion of the Tri-State area through through Friday. For the the 4th of July weekend, the models are showing minor shortwaves troughs transiting within the mid-level flow that could aid in the development of showers and thunderstorms over the area. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 532 PM MDT Sun Jun 28 2020 VFR conditions are expected to prevail through the TAF period at KGLD and KMCK terminals. Southwest winds will persist through midnight at both sites, becoming southerly around 9kts. Winds may briefly become westerly around 16Z, returning to southerly Monday afternoon at 15kts gusting to 23kts. At KMCK, low level wind shear will be possible from around 05 to 10Z. Wind shear will be from 180 degrees at 35kts around 05Z, becoming 190 degrees at 40kts around 07Z. Winds will become southeasterly again through the day Monday. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Red Flag Warning from noon MDT /1 PM CDT/ to 8 PM MDT /9 PM CDT/ Monday for KSZ001-013. CO...Red Flag Warning from noon to 8 PM MDT Monday for COZ252>254. NE...NONE. && $$ SHORT TERM...JRM LONG TERM...BW AVIATION...AW
Area Forecast Discussion
National Weather Service Wilmington NC
951 PM EDT Sun Jun 28 2020 .SYNOPSIS... Weak high pressure will remain over the area through tomorrow. A series of upper disturbances will move across the region tonight through midweek, producing daytime as well as nigh-time scattered showers and thunderstorms. A weak front will move in from the north, stalling in the region by and through the mid- week. && .UPDATE... Will be dealing with a broken line of thunderstorms arcing it`s way across the FA for the remainder of this evening. The leading edge of this line extended from St Pauls across Fairmont to Mullins and then arcing back across Evergreen to Olanta. An isolated strong to severe thunderstorm along this broken line remains a possibility until this activity pushes off the Carolina Coasts. Will re-adjust POPs and sky cover to account for the current and future movement of this activity. A steady state of light showers or stratiform light rain extends 20 to 40 miles behind this leading edge of convection. This activity is making a steady run to the East-Southeast at 20 to 30 mph and should reach and push off the Carolina Coasts between 1030pm and 1130pm. The back edge of the stratiform light rain will follow but will be dissipating as it moves across the FA. Will likely carry isolated POPs for the reminder of the overnight for all locations after the main threat and stratiform light rains push off the coast. Made some adjustments to tonights lows as well as overnight hrly temps and dewpoints, especially locations that experienced rainfall. Some tweaking of the winds over the area waters overnight, with synoptic winds generally SW-WSW at 10 to occasionally 15 kt. A few gusts could reach 30-35 kt associated with the convection that initially moves off the coast. Which will and may require MWS or SMW. Seas generally 2 to 4 ft, with the 4 footers located across the outer waters, 15 to 20 nm out, off Cape Fear south to Murrells Inlet. && .NEAR TERM /THROUGH MONDAY/... Likely an active pattern though some vexing differences in opinions between models persists. Local mid level flow will be WNW to NW around a large cutoff over the Northeast. A convectively generated vorticity max will move towards the area this evening and right away guidance is struggling to depict what happens as the system crosses the Appalachians. The WRF continues to show a rather strong convective signal in what looks very much like an MCS that transitions into a training flash-flood setup not unlike the current radar depiction across parts of TN/KY making this solution certainly appear possible. The rapid update and radar ingestion of the HRRR appears a more likely scenario in that it depicts some robust convection entering our NW zones close to sunset but then shows a weakening trend as instability wanes diurnally. Our far southern zones may not pick up much rain at all. I did chose to keep POPs in the forecast all night though as we may have a healthy outflow boundary lying NW to SE across our CWA. This boundary may end up serving as a convective focus as will the sea breeze...the intersection of the two possibly in the Cape Fear Region where POPs have been raised. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... An upper-level cut off over the northeast US will stall and provide weak pulses of energy out of the NW rotating downslope of a weak upper ridge over the central US. Showers and thunderstorms will be possible both Tuesday and Wednesday in conjunction with afternoon instability. A slightly more potent shortwave will move into the area on Wednesday evening and help with the development of late afternoon thunderstorms which could spill over into the early evening with lingering elevated instability. Temperatures will be in line with climo both days. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Cutoff low will become absorbed in the large scale flow on Thursday. Will maintain thunderstorm chances on Thursday as the positively tilted trough remains elongated over the Mid-Atlantic and Northeast US. Storms will be isolated in nature as current models show dry air may lead to limited coverage. Models continue to diverge on a solution after Thursday with both showing a weak frontal boundary pushing south out of the Great Lakes region. Thunderstorms will be likely along this frontal boundary as it progresses. The GFS model shows the front slowly progressing into the area on Friday while the ECMWF shows the front well south of the area and a dry air mass dominating the weather on Friday and Saturday. This uncertainty remains large and will prefer to lean toward the front stalling in or just south of the area as climo and previous weather pattern observations suggest. Sunday will likely introduce higher storm chances as moisture returns from the south despite the boundary weakening. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... A disturbance aloft has helped ignite scattered showers and thunderstorms across the Carolinas early this evening. As of 00Z, the leading edge of the main cluster of storms extended from Lumberton across the NC-SC border and Florence to Columbia. This cluster is pushing ESE at 30 mph and will reach and push across the coastal terminals between 2z and 4z. Expect brief periods of MVFR/IFR conditions with a few of the stronger storms producing wind gusts of 40+ kt. After 06Z, convection should settle down with only isolated activity at best. Convection will likely re-fire late Mon morning or early aftn as residual dynamics aloft press southward and have indicated this potential with Prob30 groups. Extended Outlook...Expect possible MVFR/IFR conditions from isolated to scattered showers and thunderstorms each day and night through Wednesday. This the result of a series of weak disturbances aloft moving across the area. Early morning MVFR from BR remains possible. && .MARINE... Southwesterly flow in the 10-15kt range will be the general rule through Monday night. It may grow lighter at times however as lower pressure ridge into the Carolinas trailing from an area of low pressure in the Northeast. 5-6 second wind waves along with a relatively weak 10 second SE swell will generally yield 2-3 ft seas. Offshore flow on Tuesday will continue at 5-10 knots with a typical Bermuda swell at 2 feet and 8-9 seconds. As low pressure over the Northeast US exits into the North Atlantic, southerly winds return to the area. Winds will remain 10-15 knots through the middle of the week ahead of an approaching weak frontal boundary. Lots of uncertainty exists with the position of the front and the associated winds. Regardless, wind directions and speed don`t look to be impactful. The main threat for mariners this week will be the chance of thunderstorms each day through Saturday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MBB UPDATE...DCH NEAR TERM...MBB SHORT TERM...21 LONG TERM...21 AVIATION...DCH MARINE...DCH/MBB/21
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
948 PM CDT Sun Jun 28 2020 .UPDATE... 946 PM CDT Main update this evening was to back off PoPs through early Monday for a primarily dry forecast. Previous high resolution CAM guidance that had brought convection to parts of northwest and north central Illinois toward and after daybreak was far too aggressive with upstream convection. A broken arc of thunderstorms did finally develop recently over northeast Iowa. However, steering flow is off to the northeast, so unless the thunderstorms quickly congealed and developed a cold pool, would expect them to continue tracking off to the east-northeast and stay north of our latitude. As such, the new 00z CAM guidance has supported the idea of a primarily dry overnight period. Did maintain slight chance PoPs for parts of the CWA well after midnight owing to the impressive MUCAPE reservoir sampled on the 00z DVN RAOB. Looking ahead to Monday, it appears we will destabilize quickly and erode capping. However, with the increasing likelihood of a drier start to the day, as well as general lack of large scale forcing mechanism, favored area for CI toward mid day may be in the vicinity of lake breeze convergence and perhaps differential heating boundaries as cumulus quickly blossoms. As a well modeled MCV crosses the MS River Valley toward Monday evening, that should provide a bump in large scale forcing to increase convective coverage in the mid to late afternoon to scattered (40 to perhaps 60%). A steeper mid-level lapse rate (>7C/km) plume will be over the area during peak heating, along with steep low level lapse rates. Temps inland of the lakeshore rising to near/around 90 and dew points in the 70s should yield large MLCAPE potentially near or even above 4000 j/kg. Therefore, despite generally sub-marginal deep layer shear, updraft acceleration from the large CAPE plus steep low level lapse rates should yield an isolated downburst wind threat from the collapse of tall cores. Can`t rule out isolated marginally severe hail from the deepest convection. In addition, very slow and erratic storm motions as has been typical the past few days amidst PWATs over 1.75" will support a localized flash flooding risk. High moisture content will be another element in support of isolated damaging wind potential due to precip loading of downbursts. If we can add (subtract) a few more degrees to the high temps tomorrow, which will depend on how quickly cumulus field blossoms, then heat index values of near/over 100F will be more (less) common. Castro && .SHORT TERM... 259 PM CDT Through Monday night... As has been the case, the forecast emphasis was on deciphering the primary thunderstorm chances and coverage. After spotty storms through early evening, chances then start to increase overnight into Monday morning, with at least scattered thunderstorms looking likely Monday afternoon and early evening. Similar to recent convective episodes, locally gusty winds and heavy rain will be probable with any storms. Also of note on Monday will be potential for heat index readings to peak around 100. An early reaching of the convective temperature by noon resulted in a scattered of showers and a couple storms, but also brought ample cumulus and some cold pooling, together slowing heating. Thus coverage has dropped off as of 300 PM. Additional isolated storms are possible through the early evening with the high boundary layer moisture, renewed heating with some clearing, and subtle wind discontinuity foci. There should be a relative minimum though in chances from roughly 8p-1a before gradually increasing chances overnight with strengthening warm advection aloft. The mid to upper level ridging will be quite stout, with the warm frontal zone at 850 mb lifting into this. This will steer steep lapse rates from roughly 750-550 mb into north central Illinois overnight. So it will be a question whether any scattered elevated convection can realize those lapse rates for a few strong to possibly severe storms. Convection allowing models (CAMs) have trended slightly downward with their footprint overnight, but tough to say for certain if the mid-level ridge of the elevated instability (MUCAPE > 1500 J/kg) will win out into north central Illinois. Any elevated activity will likely be on a downward trend by mid- morning, especially with any short wave/MCV focus likely moving east-northeast away from the area. However, any outflow boundaries may serve as a focus into the afternoon, in tandem with the low- level frontal zone which will be inching northeastward over the area. Confluence/convergence along this is not predicted to be strong, although it may not need to be as forecast soundings from the NAM show the convective temperatures in the upper 80s reached. In addition the air mass along this frontal zone will be characterized by dew points in the mid 70s given upstream observations near Kansas City today. It may not take much impetus in the low and/or mid-levels to spark convection Monday afternoon, but it`s another messy setup with a domino effect to any mesoscale features in advance. That will also impact temperatures on Monday that have the potential to warm to the lower 90s. If they can, heat index readings will eclipse 100. But confidence is not high on that given the likelihood of at least morning clouds and the propensity to convect by mid afternoon if pockets of strong heating do materialize. Convection that does develop Monday afternoon will be capable of strong winds and local flash flooding, as storm motions will again be on the slower end of the spectrum. With mlCAPE values expected to reach 1500-2000 J/kg, the potential for stronger downbursts is there, especially if there is any remnant MCV artifact helping to drive things. Convection should again gradually taper through the evening, though a mid-level disturbance approaching from the southwest will keep some chance into the overnight. MTF && .LONG TERM... 257 PM CDT Tuesday through Sunday... Warm, humid, and unsettled conditions look to remain in place through midweek with persistent east to southeasterly low level flow. As winds gradually turn more east to northeast later in the week, temperatures may not fall much but dewpoints and associated precip chances may decrease a bit. Midwest upper level ridging will limit the passage of larger scale synoptic systems through the area, so convective trends will mainly be driven by mesoscale effects and diurnal heating. Tuesday morning could see one of the more pronounced mesoscale systems over the area with multiple models developing an MCV upstream and lifting it into the ridge that sits overhead. Model signals suggest this activity may be waning during the early morning, likely due to a combination of unfavorable diurnal timing and the influence of the ridge, but the lingering circulation appears poised to tap into afternoon heating and generate renewed development Tuesday afternoon. Remnants of the circulation may even persist into Wednesday and support additional development that afternoon before dropping south out of the area. Following the departure of the MCV, by Thursday into the weekend winds appear favored to back more easterly to northeasterly as mentioned above. With a somewhat drier boundary layer, precip chances and overnight lows appear correspondingly lower compared to earlier in the week, but the associated reduction in cloud cover should keep afternoon highs in the mid-upper 80s to lower 90s...though cooler by the lake. Lenning && .AVIATION... For the 00Z TAFs... Aviation forecast concerns: * Timing/coverage of SHRA/TSRA potential through the period, focusing on Monday afternoon/early evening. High pressure was centered from the central Great Lakes northward late this afternoon, while a warm/humid air mass covered much of the Corn Belt to the south and west. Old synoptic boundary which sagged across the local area Friday-Saturday, while somewhat diffuse, appears to extend from southern MN across northern IL to central IN, while an old consolidated outflow boundary from a couple rounds of organized convection was farther to the south from western IA, across northeast MO into southern IL. Air mass from Chicago west and southward is characterized by temps in the mid-80s and dew points around 70, with conditionally unstable conditions topped by somewhat dry mid-level air and weak mid-level lapse rates. This has generally prevented organized convective development across the area this afternoon, though area of slightly enhanced cumulus along boundary from near KRFD to KDPA to south of KGYY could potentially produce an isolated SHRA or TSRA early this evening before sunset, as tail of mid-level trough lifting northeast across MN transits far northern IL. This appears to be fairly low probability however, and even lower prospect for directly affecting KRFD, KDPA or KGYY. The next potential period of SHRA/TSRA would be toward/after sunrise Monday morning, with some guidance depicting a decaying MCS sliding east-southeast along the warm frontal zone. 3 km WRF and some of the other WRF-based CAMS depict this, while more recent HRRR and RAP runs have backed away from this. Certainly potential for elevated convection to develop overnight across parts of IA, with southwesterly low level jet focused there atop aforementioned low level boundaries, though with better mid-level support lifting northeast into MN am more inclined to follow drier HRRR/RAP scenario at this time. Greatest potential for TSRA development across the terminals appears to be Monday afternoon, with most guidance developing convection along a combination of northeastward moving front/outflow boundaries and lake breeze boundary during peak diurnal heating. Some indication that there could be some isolated updrafts developing by late morning in the vicinity of the lake breeze boundary (which sets up early with synoptic southeast flow), but there is a much stronger signal with approaching surface boundary from about 20Z/3 PM onward as instability peaks during the mid-late afternoon. Relatively light mid-level winds would indicate slow cell movements, likely with considerable outflow boundary interaction. For this reason, threat of TSRA would likely linger into the early evening before instability decreases toward/after sunset. This would also result in a somewhat chaotic wind direction scenario modulated by what could be numerous gusty outflow boundaries. Outside of convective influence, wind should generally remain from the east-southeast. Ratzer && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSChicago www.twitter.com/NWSChicago www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1026 PM EDT Sun Jun 28 2020 .SYNOPSIS... A shortwave will move across the region this evening and tonight. Unsettled weather continues through the middle of next week as an upper low becomes stalled over New England with several weak disturbances moving across the Mid-Atlantic states. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 1025 PM Sun...Shortwave and associated vort max is positioned along the Appalachians this evening per WV imagery and continues to slow dig towards the Carolinas. The continued southward trend in guidance with the convective cluster over the NC/SC border and only very spotty shower activity over our CWA. Short range guidance (including the 01Z HRRR to a lesser degree) continued to initialize this feature too far north, and do show a second round of showers and storms diving across the same area overnight as the shortwave digs into the region. Think this will also track further south than indicated but uncertainty is high, so have a broader than normal slight chance PoP mainly from Highway 264 south. Best chance of activity, if any, will be along or south of Highway 70. The North Carolina Department of Environmental and Natural Resources has issued a Code Orange Air Quality Action Day for Fine Particulates through midnight tonight for the Saharan desert plume which will move over the area through at least tonight. The large swath of Saharan dust is expected to create hazy skies and unhealthy breathing conditions where the dust is most concentrated. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... As of 330 PM Sun...The aforementioned shortwave will pass overhead around sunrise, sliding south and east of the area with subsidence developing behind it late morning through midday. This subsidence will keep mainly dry conditions in place through the morning hours and potentially into the early afternoon, but will weaken by mid afternoon, allowing the chance for thunderstorms to come back into the forecast. Afternoon precip focus will be mainly along and ahead of the sea breeze, which will once again be slow to progress inland in WNW low level flow. Ample instability will be in place, but limited shear and DCAPE will keep the severe threat low overall. Temps near normal will continue. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... As of 4 AM Sunday...A trough will dig down the eastern seaboard through much of the coming week, bringing off and on scattered showers and storms to the region. Monday Night through Thursday...Upper level low pressure will close off from the background westerlies and drop over the Northeast and Mid Atlantic region, with several weak shortwaves traversing the general troughing that will extend over the Carolina Coast. Ocnl periods of unsettled weather will prevail through much of the week, though not a washout by any means. Will forecast pops in the slight chance to chance range, with the highest chances coinciding with typical diurnal showers and storms each afternoon, highest chances along typical sea/sound breeze zones and Coastal Plain region. Relatively seasonable airmass prevails at the surface as Bermuda High continues to ridge in the from east with troughing inland, and daily temp trends will be primarily dependent on precip timing and cloud cover. Friday and Saturday...The upper low over the Northeast region fills Thursday with the upper trough axis sliding to the south by Friday, which may lead to lower precip chances late in the week. However, guidance is showing lingering troughiness over the lower Mississippi and Tennessee River valleys may develop into another closed low late in the week. Depending where this sets up, ENC may remain in a more unsettled pattern, but as with most closed lows, predictability is low, especially this far out. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Short Term /through Monday/... As of 740 PM Sun...VFR at all sites this evening with increasingly isolated showers moving into the coastal plain this hour. Shortwave trough over the Appalachians in VA will continue to drift south tonight and help nudge convective activity currently over northern SC east tonight towards coastal NC. Guidance trends have been slower and further south in regards to convective activity, and it appears increasingly likely PGV/ISO will get through the evening without much activity. OAJ remains the most likely and maintained the TEMPO group with a minor slowdown in timing. Typical convective-associated restrictions are expected to last less than an hour. VFR conditions prevail in this feature`s wake overnight into tomorrow with subsidence aloft into the first half of Monday. Some sea breeze convection could introduce potential impacts for OAJ/EWN tomorrow afternoon. Long Term /Monday Night through Friday/... As of 430 AM Sunday...Unsettled weather will prevail much of early to mid week, with periods of sub VFR possible. && .MARINE... Short Term /through Monday/... As of 340 PM Sun...Broad low pressure stretching from New England to the Mid-Atlantic and high pressure across the Gulf of Mexico and Caribbean will keep moderate WSW to W winds in place through tomorrow. Gusts to 20 kt this afternoon will bring seas to 3-5 ft for areas exposed to SSW wind swell this evening, but seas will subside some overnight as the windswell diminishes, and 2-4 ft seas prevail once again on Monday. Long Term /Monday Night through Friday/... As of 430 AM Sunday...A trough will persist near the area through the long term with generally light winds around 15 kt or less. Wind direction will depend on the location of the trough with mainly a southerly direction with the trough north of the waters, however the trough may sag south of the area Tuesday with winds briefly becoming N to NW, and may sag back into the waters again Thursday. Seas expected to remain around 2-3 ft through the period, occasionally building to 4 ft across the outer portions of the central/southern waters. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...MHX NEAR TERM...MS SHORT TERM...CB LONG TERM...SK AVIATION...SK/MS MARINE...SK/CB
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
700 PM CDT Sun Jun 28 2020 .SHORT TERM...(This evening through Monday night) Issued at 401 PM CDT Sun Jun 28 2020 MCV moving into the Mankato area will be the focus for thunderstorms this afternoon that will track up into the Twin Cities and eventually the Twin Ports region. We`re starting to get hints of deep moist convection initiating, though to this point, this feature has been fairly stable. However, with over 5000 j/kg of MUCAPE up into western IA, persistent southerly flow will continue to push more unstable air northward, so agree with the HRRR and HopWRFs that we will eventually a cluster of storms develop that moves north through the Twin Cities later this afternoon. Again, with the better instability and shear off to the southwest, these storms look to remain sub-severe. After this MCV moves through, attention turns to threat for where storms develop along the warm front. This next round of storms will tap into the extreme instability down across IA, but there continues to be little continuity in the models with where this batch of rain ends up. For example, the HRRR between 12z and 18z look fairly similar, the only difference is the 12z HRRR had the evening/overnight storms from south central MN up into the Twin Cities, while the 18z shifted it all north, with the heavy rain from the Twin Cities/east central MN into northwest WI. At this point, still favor a more southern solution like what the 12z HREF and 15z HopWRF mean have, with the warm front ending up from about Marshall to the MN/WI/IA border, with the greatest heavy rain and severe risk through the night centered closer to that region. Both the 12z and 18z HRRR show the potential for training of storms along where the warm front sets up, with some areas receiving 3+ inches of QPF. Fortunately, antecedent soil conditions are dry, so really think to have much of a flash flood threat, we`re going to need to see heavy rain in the urban core of the Twin Cities metro. Everywhere else, soils are dry enough to handle some good rains. For the severe threat, that again looks better closer to the MN/IA border, where instability will be greater and shear is increased by the jet streak currently apparent on satellite imagery over KS moving up over IA this evening. For the severe threat to materialize, we probably need the souther solution to work out (12z HRRR). If we see a more northern solution as we are seeing with the 18z HRRR and the 18z HopWRF members just rolling in, we`ll likely have a lower severe threat as these areas will be displaced from the stronger instability and shear. This activity tonight will likely generate an MCV, that will then serve as the focus for thunderstorm development Monday afternoon. There was certainly a trend from the GFS/NAM for the MPX area to be hot and capped on Monday, but like the idea of the 18z HRRR. Because of where it develops convection tonight, the HRRR generates an MCV near the Twin Cities, that by Monday afternoon is up by Duluth, with storms initiating there then tracking southeast into western WI. This should be how things play out, it`s just a matter of where that MCV ends up and given uncertainty with where that will be, have kept PoPs mainly in the 30s north of I-94. As you get southwest of I-94, you will be encountering stronger and stronger capping, so have a dry day for Monday by the time you get to south central, southwest, and west central MN. With the lower cloud cover and drier conditions expected, this will translate to hot conditions southwest of I-94, with afternoon heat indices forecast to be in the mid 90s to lower 100s. Haven`t issued any heat headlines yet until we get a better handle on how clouds and convection will trend Monday afternoon, but a heat advisory is looking pretty likely for at least the Twin Cities metro on Monday. .LONG TERM...(Tuesday through Sunday) Issued at 401 PM CDT Sun Jun 28 2020 For the long term, Tuesday is looking hot and dry, with the best forcing for precip out in the Dakotas. Wednesday/Wednesday night still looks to feature the passage of a weak cold front, but both the GFS/ECMWF trended drier with it. This makes sense as the main upper wave forcing this front will be going from the Dakotas into northern Saskatchewan. So forcing and shear will be weak across the MPX area with the front, with the severe threat really driven by the presence of strong instability along the front. Behind the front we see building heights and a drying trend for Thursday through Saturday. Stuck with NBM PoPs for Thursday, though those look overdone. Really it doesn`t look like we have much of precip threat until Sunday, when a weak cold front looks to drop down from the north. For temperatures, it still looks hot, with the potential for us to pile on quite a few 90+ degree highs through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 700 PM CDT Sun Jun 28 2020 MCV moving through now bringing an initial round of storms. Still some uncertainty with where the next round develops. The HRRR has been bouncing around with where storms develop through the rest of the night, but it has been bouncing additional storm development around east central MN and western WI. Kept the similar theme going with previous TAFs, but there`s still plenty of potential for things to work out differently. Looks like MVFR cigs are going to be confined closer to the MCV circulation in central MN, so kept MVFR mention confined to AXN/STC, with models trending away from MVFR or lower cigs elsewhere. For Monday, the trend continues to be for drier conditions, with best TS potential in WI, but confidence in TS occurring is not high enough to include in the TAFs. KMSP...MCV related precip will be off the field by 1z. After that, it`s wait and see if we get another round. That next round looks to get going near or shortly after 6z, possibly persisting out to 12z Monday. CIG trends have been to back away from MVFR potential, so kept MSP VFR outside of TSRA, with a SCT cloud group at the MVFR to handle that threat. /OUTLOOK FOR KMSP/ Tue...Mainly VFR. Slight Chc TSRA/MVFR. Wind SE 15G25 kts. Wed...Mainly VFR. Chc TSRA/MVFR. Wind SE 5-10 kts. Thu...Mainly VFR. Chc TSRA/MVFR. Wind lgt and vrb. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...MPG LONG TERM...MPG AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
717 PM EDT Sun Jun 28 2020 .SHORT TERM...(This evening through Monday) Issued at 258 PM EDT SUN JUN 28 2020 Water vapor imagery and RAP analysis show a mid-level trough deepening into the Pacific NW. Downstream, a ridge is building through the Upper Mississippi Valley to Hudson Bay while a trough extends from eastern Canada into the ne U.S. Sfc high pres associated with the mid-level ridge extends from Hudson Bay southward across the western Great Lakes today. Higher dew points in the mid to upper 50s along with steep sfc-850 mb lapse rates has led to some diurnal cu forming across much of interior U.P. this afternoon. Temps thus far have generally reached into the lower to mid 80s across the interior with cooler readings in the mid to upper 70s near the Great Lakes shores due to lake breezes and onshore flow. Tonight into Monday, mid-level ridge will continue to build tonight with the axis slipping very slightly eastward. Over the last few days, the main question for the first part of this week has been whether shortwaves lifting through the Plains will be able to cut into the ridge or will be deflected around it. That process begins tonight as the first shortwave, now over SD/IA, lifts ne. For several days the GFS has generally been the most aggressive of the models with the wave cutting into the ridge, but now it appears other many of the other models are falling in line with the GFS, bringing rain into at least the western third of the U.P. tonight into Monday. Instability of MUCAPE values of 1000-1500 j/kg and lift at the nose of 25-30 knot LLJ will aid development of possible thunderstorms, although with weak deep-layer shear forecast strong storms are unlikely. Will continue to include chance to slight chance pops into the western third of the U.P. late tonight into Monday. Min temps tonight will range from the lower 50s interior east to the lower 60s for southerly flow downsloping locations along Lake Superior west and north central. Max temps on Monday under mostly sunny to partly cloudy skies will be well into the 80s over much of the interior with lake breezes keeping temps cooler near the Great Lakes, in the mid to upper 70s. .LONG TERM...(Monday night through Sunday) Issued at 316 PM EDT SUN JUN 28 2020 ...VERY WARM TO HOT CONDITIONS WITH HIGH HUMIDITY THIS WEEK... Omega pattern across the US and southern Canada will dominate the pattern through the middle of the week. This pattern will position an anomalously high upper level ridge centered over Hudson Bay but extends southward toward the Gulf Coast and US/Mexico Border. Further west, deep anomalous troughing over the western CONUS will likely surge shortwaves northward across the Central Plains into Canada early in the period and depending on the strength and position of the ridging, there could be an opportunity for precip in the western UP. Toward the end of the week, deep troughing to the west is progged to relax as ridging extends further west, essentially encompassing much of the central and western CONUS by Thursday and Friday. The main story this week will be the heat. The weak mid-level steering flow will allow 850mb temperatures to remain around 18-20C through the week. As a result, day time highs in the upper 80s and low 90s will be possible through the week. We may even challenge some extended heat records this week. By the lakeshores, temps should be a little cooler, especially on Thursday when northerly flow off Lake Superior is expected. Dewpoints will also be on the high side, with some guidance suggesting very uncomfortable, sometimes borderline oppressive Tuesday and Wednesday in the west. Given overnight lows in the low to mid 60s coupled with the high dewpoints, very little overnight relief should be expected. It`ll be important this week for folks and our four legged family members to stay hydrated! Model guidance continues to show a shortwave trying to undercut the upper level ridging just to the west on Monday. Much of Monday night will largely depend on the status of this wave and how effective this push will be. For the moment, guidance suggests convective pulsey thunderstorms will be possible in the far western UP and the western portions of Lake Superior. Given the aforementioned weak mid- level flow, weak shear profiles are expected and severe weather isn`t a primary concern; the caveat being the amount of CAPE could certainly be enough to support some healthy updrafts. The bigger hazard associated with any shower or thunderstorm activity will be rainfall. With the increasingly moist airmass settling over the west and model guidance suggesting PWATS greater than or equal to 1.75 inches, heavy rainfall will be possible. Upper level ridging and weak steering flow will slow the northward progression of this low, keeping persistent chances of precip in the west through Tuesday night. High pressure over eastern Lake Superior into Lower Michigan will keep the east largely dry during this time. Beyond Tuesday, this high will gradually shift west. Other then a chance of some thunderstorms on Thursday, this looks to keep the region mainly dry for the remainder of the week. At the moment, the overall pattern suggests the very warm and hot conditions will continue through the upcoming holiday weekend. In terms of shower and thunderstorm activity, we`ll have to keep tabs on how a shortwave moving through Canada will evolve on Saturday through Sunday. Its possible that we could have some thunderstorm activity Saturday into Sunday, but given the guidance`s lack of consistency, confidence is pretty low. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 716 PM EDT SUN JUN 28 2020 VFR conditions at KIWD/KCMX/KSAW are expected thru this fcst period. Winds at the sfc for KIWD, KCMX, and KSAW will be 10 kt or less until a little bit past noon for KSAW, when winds could gust closer to 20 kt. Also, KIWD could very well expect some on-and-off LLWS between 04z to 12z. Still have reservations on whether shra/tsra happens near KIWD, as models are not all in agreement. However, there is enough confidence that shra/tsra will be approaching KIWD early Monday morning to warrant at least a VCTS. If a TS or SHRA does occur over KIWD, vis and cigs could rapidly deteriorate. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 258 PM EDT SUN JUN 28 2020 Through midweek, sfc high pres will ridge back from southeast Canada into the Great Lakes while a low pres trough drifts out over the Plains. A relatively weak pres gradient will result in winds under 20kt across Lake Superior over the next several days. However, there may be locally enhanced winds each aftn/evening that may gust to 20- 25kt. Patchy fog noted on satellite imagery may persist into tonight. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...JP AVIATION...TAP MARINE...Voss
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 325 PM CDT Sun Jun 28 2020 We are in a wait and see pattern if and when convection will develop in our area. After this morning`s round of severe storms, skies cleared out, but have also become partly to mostly cloudy with daytime heating. An outflow boundary has triggered scattered thunderstorms across south central IA, and satellite hints at this possibly extending west into our area, with hints of some TCU trying to develop between Plattsmouth and Tekamah. CAMs have generally been all over the place this morning, initially keeping storms out of the area, but the HRRR has lately indicated some development between Omaha and Sioux City yet before 00z. There isn`t much upper level support, so that may be a limiting factor. The atmosphere is extremely unstable, with MLCAPE around 4000 J/Kg, but perhaps just slightly capped with less then 25 J/KG of CIN. Best scenario is that something could develop in the aforementioned area, and it`s within this area that SPC has also continued the slight risk. There are also a couple of CAMs that develop and MCS over northwest IA, and the tail end could ride down the Missouri River valley late this evening and overnight, so we`re not discounting that completely. Meanwhile, the Saharan Dust layer arrived. It`s generally undetectable on our various GOES16 dust products, but certainly showing up in observations and pictures with visibility down to 5 miles in many locations. Airnow.gov indicates air quality is in the moderate range in Omaha and in the unhealthful range for sensitive groups in Lincoln. Hard to get a good handle on the forecast for this, but a NASA model of Dust Aerosol Thickness suggests some slight improvement by tomorrow. It`s also incredibly humid out there with dewpoints in the mid to upper 70s, making it feel like the mid to upper 90s. The dewpoint even hit 80 for one observation at Nebraska City at 155 pm. Monday should be hot, humid, and dry. To match up with the NWS in Sioux Falls, we will issue a heat advisory for Knox/Cedar counties along the Missouri River where heat index value will range 100-105 during the afternoon. There could be spotty nighttime convection Monday night on the nose of the low level jet underneath the upper ridge. Not a clear signal, but it`s only a 20% chance. Tuesday looks dry, and hot and humid weather continuing. There remains a decent signal in the models for storms increasing Tuesday night into Wednesday. But it`s now looking dryer Thursday into Friday. Model blends indicate a 20-30% chance for storms next Weekend. And while it`s the holiday weekend, and we`d like to provide more definition, that`s trending moreso toward climatology than anything at this point. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 632 PM CDT Sun Jun 28 2020 VFR conditions to prevail for the TAF period. Winds are currently gusting up to 30 kts across the area including at KOMA and KLNK. Wind speeds are expected to lower in the next hour or two. The wind direction will remain southerly. There is a slight chance for thunderstorms this evening over western Iowa and the Omaha area. The probability isn`t high for this and will likely require a TAF amendment to capture. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from 1 PM to 7 PM CDT Monday for NEZ011-012. IA...None. && $$ DISCUSSION...DeWald AVIATION...Fajman
Area Forecast Discussion
National Weather Service Shreveport LA
1042 PM CDT Sun Jun 28 2020 .UPDATE... Only a few minor changes to forecast to account for current trends. Otherwise, the remainder of the forecast remains the same. A disturbance will move across the northwestern half of the region tonight, providing forcing for showers and isolated thunderstorms to continue during the overnight period. The best chances will be across SE Oklahoma and along and north of the Interstate 30 corridor of NE Texas and SW Arkansas. Cloud cover will remain across the region, limiting radiational cooling, so temps will only fall a few more degrees into the mid to upper 70s tonight. Winds to remain from the SSE between 5 to 10 mph. /20/ && .PREV DISCUSSION... /issued 758 PM CDT Sun Jun 28 2020/ AVIATION... Scattered showers and a few isolated thunderstorms remain across the region this evening, but VFR conditions have continued to prevail. This activity should start to decrease in coverage by 04z with the exception being at Texarkana where showers/t-storms may linger through 06z. Ceilings will become MVFR during the pre- dawn hours and linger into the mid-morning across the terminals before returning to VFR by late morning through the remainder of the day. Additional scattered diurnal convection will be possible by tomorrow afternoon at all the TAF sites. /20/ && PREV DISCUSSION... /issued 258 PM CDT Sun Jun 28 2020/ SHORT TERM.../Tonight through Monday Night/ The latest RAP mid-level analysis indicates that a 500mb high pressure ridge is centered over the eastern Gulf of Mexico. The local area is on the northwestern side of this feature in a southwesterly mid-level flow. A weak short wave is sliding northeastward into northeast Texas. At the surface, a 1019mb high is located over the eastern Gulf with a broad area of high pressure across much of the Southeast. Locally, on the west side of this feature, the area is in a southerly low-level flow that is continuing to advect a moist and humid air mass from the Gulf into the area. Scattered showers and isolated thunderstorms have developed with a few strong gusts in central Louisiana. This evening, the mid-level short wave will continue to slide northeast into southeastern Oklahoma. This feature will provide forcing with strong instability in place (SBCAPE 3000-3500 J/kg), allowing for scattered thunderstorms to continue across much of the area. All members of the 12Z Storm Prediction Center (SPC) High Resolution Ensemble Forecast (HREF) simulated radar support that this with thunderstorms beginning to decrease late this evening. In a weakly sheared environment, do not anticipate the storms to become severe, although a few may become strong with gusty winds possible. A surge of deeper moisture will move into the area with PWAT values increase to near 2" into the evening and thus a few of the storms are anticipated to have locally heavy downpours which may lead to localized ponding in flood prone areas. One possible limiting factor for storms into the evening is any remnants of the Saharan Air Layer, which will make for hazy conditions with dust bringing visibilities to the 5-10SM range. This layer of dust, which appears to be washing out and is difficult to depict on satellite imagery, may assist in shortening the lifespan of thunderstorms, maturing more quickly to their dissipating stage and raining out. With all of this in mind, based on current development moisture is deep enough to overcome any suppression from the thinning Saharan Air Layer. The short wave energy will shift further northeast of the area overnight. This feature will provide forcing for some showers and thunderstorms to continue overnight. In addition, with some upstream convection in Texas that may push into our area as it is weakening, have the chance of showers and thunderstorms continuing overnight and becoming limited to southeastern Oklahoma, northeastern Texas and southwestern Oklahoma by the pre-dawn hours. On Monday, the area will remain in a southwesterly mid-level flow and will be in the wake of a short wave pushing northeastward into the Missouri Valley. Forcing will be lacking for the most part throughout the day with the hot and humid pattern continuing. Still, strong instability should be sufficient for the development of at least isolated diurnally driven thunderstorms. The best chance for thunderstorms on Monday appears to be across southeastern Oklahoma and southwestern Arkansas, where a short wave will pass to the northwest. On Monday night, any lingering showers and thunderstorms should diminish with yet another hot and muggy night in the forecast. For temperatures, it will be a warm and muggy night overnight with lows in the mid to upper 70s. Highs on Monday are a degree warmer than the NBM and will range from the mid 80s in McCurtain County, Oklahoma to the lower 90s in East Texas, Deep East Texas, and northern Louisiana. Heat indices will approach 100F across much of the area with a few locations again coming near Heat Advisory criteria of 105F. A Heat Advisory will probably not be needed tomorrow as even locations that hit criteria today probably will be just below criteria tomorrow. For an advisory it is required to have two consecutive days of heat indices above 105F. Overnight lows on Monday night will be in the mid 70s across much of the area. /04-Woodrum/ LONG TERM.../Tuesday through Sunday/ Upper level ridging over the Gulf of MX will begin to expand N across TX and the Lower MS Valley Tuesday, and into the Midwest and Mid MS Valley through Thursday, resulting in hotter temperatures as we enter the month of July. A weak perturbation aloft may ride atop the ridge Tuesday and may contribute to the development of isolated convection over SE OK/SW AR/portions of Ncntrl LA, but the moisture profile looks to remain shallow which may negate any development over these areas. Did maintain slight chance pops over these areas in the afternoon, which should diminish by sunset if they develop. The main story though through the first half of the long term period though will be the heat, with max temps likely reaching the mid 90s over much of the area Tuesday through Thursday, with dewpoints likely not mixing out much during the day given the stagnant pattern in place and likely to persist. Thus, heat indices may be approaching Heat Advisory criteria in some areas especially by Wednesday and Thursday, with later forecasts continuing to refine this threat. Any convection Wednesday will remain isolated at best over portions of Scntrl AR/Ncntrl LA, but a weakness remains progged by the ECMWF/GFS to develop over the Mid MS Valley Thursday before sliding S along the Ern periphery of the amplifying upper ridge as it expands into the Dakotas into the Nrn Great Lakes region. There has been consistency amongst the progs the last couple of days with convection developing along an attendant sfc trough Thursday afternoon from Nrn OK into Ncntrl AR and the Mid-South region, with this convection possibly building SSE across Ern OK through much of AR through the evening, and thus have included low chance pops for the Nrn and NE zones, with this convection possibly building into the region Thursday night and Friday as this shortwave trough continues to slide S. Have maintained consistency with the previous forecast in undercutting pops for now given that it is 5-6 days out, as this convection will likely be diurnally and mesoscale driven, and have trended low to mid chance pops over the region Thursday night through Friday night. May also have to contend with compressional heating Thursday afternoon across SE OK/Nrn sections of SW AR near and just S of the approaching weak sfc trough, but believe the convection Thursday night through Friday will alleviate the heat somewhat while also resulting in slightly lower dewpoints. Could still see sct convection persist across the region Saturday as the sfc trough lingers over the area, with more isolated convection Sunday as we become more influenced with the Ern extent of the large Cntrl CONUS ridge. Should this weak troughiness cut off though over the Lower MS Valley (as suggested by the 12z ECMWF/GFS), then a continued unsettled weather pattern will persist for at least portions of SW AR/N LA through the remainder of the holiday weekend into the first full week of July. && .PRELIMINARY POINT TEMPS/POPS... SHV 77 92 76 93 / 20 30 10 10 MLU 74 91 74 93 / 20 30 10 20 DEQ 74 88 74 90 / 40 50 10 20 TXK 76 88 75 91 / 30 40 10 20 ELD 73 89 73 92 / 20 40 10 20 TYR 76 91 76 93 / 30 20 10 10 GGG 76 92 76 93 / 20 20 10 10 LFK 77 92 76 94 / 20 10 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 20